So I recently did allot of research about the idle shudder and misfire at start up only to find that it is a common problem with almost all 08' GXP Solstice and Skys. Even after replacing the spark plugs with the newer "hotter" range for cold start characteristics, if your car warms up and drives normal except for when you stop and idle, you then get the dreaded "idle shudder" effect, then your fuel injectors could be at fault. I found several threads related to this same issue. Owners bringing in their cars time and time again with no results of finding the source of the problem until the fuel injectors are tested. Then they come back saying they need to be replaced because they are either leaking or just bad. So how many have had their injectors replaced on an 08' GXP or Redline? Seems to be only this year that has this problem. I think GM should fix this for free. My 08' only has 25k miles on it. The injectors should last longer than that.